Adjustable tension device for sewing-machines.



W. L. DAVIS & F. L. VAN ALLEN. ADJUSTABLE TENSION DEVICE FOR SEWING MACHINES.

APPLICATION FILED MAY 29, 1914. 1,125,975., Patented Jan. 26, 1915.

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APPLICATION I'ILED MAY 29, 1914. 1,125,975, Patented Jan. 26, 1915.

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UNITED STATES PA" onrron WILLIAM I1. DAVIS AND FRED IJ- VAN ALLEN, OF DAYTON, OHIO, ASSIGNORS T0 TI-IE DAVIS SEWING MACHINE COMPANY, OF DAYTON, OI-IIO, A CORPORATION OF OHIO.

ADJUSTABLE TENSION DEVICE FOR SEWING-MACHINES.

Specification of Letters Patent.

Patented J an. as, 19115.

Application filed. May 29, 1914. Serial No. 841,930.

To all whom it may concern:

Be it known that we, WILLIAM L. DAVIS and FRED L. VAN ALLEN, citizens of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Adjustable Tension Devices for Sewing-Machines, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to adjustable tension devices for sewing machines and the like.

Sewing machines that go into domestic use, and even those that go into commercial use, are ordinarily used for work of widely difierent kinds and with threads of various sizes. In order that the work may be properly done it is necessary that threads of different sizes be subjected to different tensions and likewise it is necessary that in sewing unusually heavy materials a much heavier tension should be employed than. in sewing ordinary materials, and, when sewing lighter materials, a much lighter tension.

should be used than on ordinary materials. Adjustable tensions have been proposed heretofore to take care of these variations but the adjustment was left wholly to the operator and unless the operator was highly skilled it frequently happened that a very considerable quantity of bad work would be done before the proper adjustment was secured.

The object of the present invention is to provide a tension device of this character with means whereby the springs may be quickly and certainly adjusted to give the best tension for the particular class of work which is to be done and to so construct the device that when the spring is placed under a certain tension the device will accommo date itself, without action on the part of the operator, to various sizes of threads and to the ordinary variations in working conditions or materials; and further, to provide means, positive or otherwise, for limiting the movement of the adjustable parts to enable the adjustment to be made with certainty. And a further object of the invention is to provide a device of this kind which will be of a simple durable construction which may be readily assembled and in which the adjustable parts may be locked in their assembled positions, thus preventing the parts from being accidentally moved out of their proper relative positions.

In the accompanying drawings, Figure 1 is a side elevation of the head of a sewing machine showing our invention applied thereto; Figs. 2, 3 and 4: are side elevations of the adjustable tension device showing dilierent adjustments thereof; Fig. 5 is a longitudinal section taken centrally of the tension device; Fig. 6 is atransverse, sectional view taken on the line a w of Fig. 5 and looking in the direction of the arrows; and Fig. 7 is a sectional view, taken on the line y y of Fig. 5 and looking in the direction of the arrows; Figs. 5, 6 and 7 being on an enlarged scale.

In carrying out our invention we provide tension members arranged to receive the thread between them and to offer resistance to its forward movement. A spring is arranged to act on one of these tension members to cause the necessary pressure to be exerted upon the thread. By adjusting the tension of this spring we secure the desired pressure or tension upon the thread. The tension of the spring may be adjusted in any suitable manner. Preferably this is accomplished by a rotatable adjusting device and cooperating with this adjusting device are suitable means for limiting its movement. Such means are provided to position the adjusting device at one point where it will cause the thread to be subjected to the least tension with which it is desirable to work; and at a second point where it will cause the thread to be subjected to the greatest tension with which it is desirable to work. Between these points are means for so positioning the adjusting device that it will give a satisfactory tension under all ordinary conditions of work and will accommodate itself to threads of various sizes or numbers. The means for limiting the movement of the adjusting device, or positioning the same, may be of any suitable character and at the two extremes of move ment of the device these means are preferably in the form of positive stops, to facilitate the movement of the adjusting device into either of these positions. These results may be secured with mechanisms of various kinds and the device herein shown and described has been chosen for the purpose of illustration only.

In the accompanying drawings, we have illustrated the tension device in Fig. 1 as applied to the head, 1, of an ordinary sewing machine, the device being indicated as a whole by the reference numeral 2. As here shown it is mounted on the front of the head but it will be understood that it may be mounted on the face plate or in any other suitable position. In the form here illustrated the device comprises two tension members 3 and 4 which are shown in the form of disks mounted upon a stud 5 which is rigidly secured to the head of the machine. The disks have their peripheral portions bent in opposite directions so as to form a peripheral groove about the same to receive the thread and guide it between the two members. The inner member 3 bears against a suitable fixed surface which, in the present instance, is the side wall of the head, but it will be obvious that any suitable surface will serve to support this tension member in a proper position. The second tension member 4 is loosely mounted on the stud 5 and is moved toward the member or plate 3 by means of a spring 6 which is coiled about the stud and arranged to exert pressure upon the plate 4.

The spring 6 is preferably mounted within a casing 7 which is supported on the stud 5 and is held against rotation relatively thereto. To this end the stud is here shown as slotted, at 8, and the base plate of the casing 7 is apertured at 9 and has a bar 10 extending across the aperture and through the slot in the stud. The outer end of the stud is screwthreaded and has mounted thereon a knurled nut 11, having an inwardly extending boss 12 011 which is mormted a sleeve 13 which, when the device is fully assembled, is secured to the nut by meansof a set screw 14 to cause it to rotate therewith and, in effect, to form a part thereof. The inner surface of the nut bears against the outer end of the spring and, consequently, the rotation of the nut, to cause it to travel along the stud, will increase or decrease the tension of the spring and the pressure which is exerted 6 upon the tension member 4:. The nut and the casing are provided with cooperating means to position or limit the movement of the nut so that it can be instantly and accurately moved into position to give the desired tension. These means consist in part of marks or indications arranged on the respective parts and adapted to be brought into alinement when the desired adjustments have been accomplished. The casing 7 ishere shown as provlded with a single mark or line, as shown at 15, while the nut is provided with three of these marks accompanied by the words Tight, Loose and Auto. Then the mark accompanying the word Tight is brought into alinement with the mark 15 on the cassion with which it is desirable to work on any class of material. 'When the mark accompanying the word Loose 1s brought into alinement with the mark 15 the adjusting devices will have been moved into a position to give the least tension with which it is-desirable to work on any material. The Word Auto and its'accompanying mark are arranged at an interme diate point between the words Loose and Tight and when this mark has been brr'mght'into alinement-with the mark 15 the adjusting devices will have been set at a carefully chosen intermediate point at which the tension Will'be adaptable to all ordinary classes of work and will accommodate itself to threads of different sizes, exertingupon the small threads a very light tension and upon the larger threads-a heavier tension. \Vh'en the adjusting devices are at this intermediate position the tension is what is known as an automatic tension, that is, it will accommodate itself to the variations in the work and thread without action on the part of the operator. In order that the adjusting nut may be quickly and accurately moved to either of its extreme positions we have provided stops to positively limit the movement of the nut. As here shownthese stops comprise a pin 16 projecting inwardly from the wall of the casing 7 and a second pin '17 carried by the sleeve -l3 0f "the nut 11 and, when the parts are in their fully assembled position, project-ing into the path of the pin 15 and adaptedto engage this pin when the nut is turned in either direction. This arrangement allows-of approximately one full rotation of the nut and the pitch of the thread is such that this rotation will give the desired variations in the tension.

The operationof the device will be readily understood from theforegoing description. and it will be apparent that after the device has been assembled and mounted on the machine all that is necessary for an operator to do to adjust the tension for ordinary work .is to rotate the nut 'to bring it into its automatic positiorg in whichposition the tension members will automatically accommodate themselves to the differentsizes of threadordinarily used and will exert on the thread the tension necessary for the usual classes of material. If it is desired to sew a very light or flimsy ma terial, such as mull, very fine lawns or the like, the nut is turned in the direction to bring the word Loose in alinement with the mark 15 and when the movement of the On the other hand, if

leather are tobe sewed the nut is turned in the opposite direction until its movement is checked by the stops when the adjustment will be accurate for these heavy materials. Thus, it will be observed that the operation of the tension device requires absolutely no skill on the part of the operator and after it has been set up and adjusted at the factory it can not become disarranged because the set screw 14 looks the parts in their assembledpositions and prevents the accidental disarrangement thereof. It will be understood, of course, that the sleeve 13 is first placed in position in the casing and the nut proper then screwed onto the-stud and the boss caused to enter the central aperture of the sleeve. After the proper adjustment has been secured the set screw is placed in position and the parts held in these positions. The nut can not then be removed because it can not be turned beyond the limiting stops.

While we have shown and described one embodiment of our invention it will be understood that this has been chosen for the purposes of illustration only and that we do not desire to be limited to the details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent, is

l. A tension device comprising a stud, cooperating tension disks, a spring coiled about said stud and arranged to exert pressure on one of said tension disks, a nut screwed onto said stud to regulate the tension of said spring, said nut having a stop extending from the inner face thereof along said stud, a second stop mounted close to said stud, extending across the path of the first-mentioned stop and held against movement relatively to said nut, whereby the movement of said nut is positively limited.

2. A tension device comprising cooperating tension members, a spring to exert pressure on one of said members, a casing surrounding said spring, and a rotatable device to regulate the tension of said spring, said rotatable device and said casing having means cooperating to position said rotatable device in any one of three positions to give respectively the maximum or minimum tension or an. intermediate tension, said means comprising a device to positively stop the movement of said rotatable device in two of said positions.

3. A tension device comprising cooperating tension members, a spring to exert pressure on one of said members, a rotatable device to regulate the tension of said spring and having a part forming a stop, and a casing surrounding said spring, held against rotation and having a stop arranged to be engaged by the stop of said regulating device when the latter is rotated.

4. A tension device comprising a stud, cooperating tension members, a spring coiled about said stud and arranged to exert pressure on one of said tension members, a casing surrounding said spring and held against rotation relative to said stud, and a nut mounted on said stud to regulate the tension of said spring, said nut and said casing having cooperating means to accurately position said nut to give a maximum or minimum tension.

5. A tension device comprising a stud, cooperating tension members, a spring coiled about said stud and arranged to exert pressure on one of said tension members, a casing surrounding said spring and held against rotation relatively to said stud, and a'nut mounted on said stud to regulate the tension of said spring, said nut and said casing having cooperating means to positively limit the movement of said nut in either direction.

6. A tension device comprising cooperating tension members, a spring to exert pressure on one of said tension members, a casing inclosing said spring and having its outer end open, a stop projecting inwardly from the wall of said casing, a rotatable device to regulate the tension of said spring, said rotatable device having a part extending into the open end of said casing and provided with a stop to engage said first-mentioned stop and limit the movement of said rotatable device.

7. A tension device comprising cooperating tension members, a spring to exert pressure on one of said members, a rotatable device to regulate the tension of said spring, said rotatable device having a stop, and a fixed part cooperating with said stop to limit the movement of said rotatable device, said rotatable device being adjustable relatively to said stop.

8. A tension device comprising cooperat ing tension members, a spring to exert pressure on one of said members, a rotatable de vice to regulate the tension of said spring, said rotatable device having a stop, a fixed part cooperating with said stop to limit the movement of said rotatable device, and a separable connection between said rotatable device and said stop, whereby said rotatable device may be adjusted relatively to said stop when the latter is in engagement with said fixed part.

9. A tension device comprising a stud having its outer end screw-threaded, -cooperating tension members, a spring coiled about said stud and arranged to exert pressure on one of said tension members, a pin mounted adjacent to said stud and held against movement relatively thereto, a nut screw-threaded on the outer end of said stud and having a" separablepart, said sep arable part having: a stop, andmeans'to sei cure together the two partsof said nut.

10.-A tension device comprising a stud having its outer end screw-threaded, cooperating tension members mounted on said stud, a springcoiled about said stud and arranged to exert pressure on one of said tension members, a casing surrounding said stud and in'elosing said spring, said casing having'an inwardly projecting pin, a nut screw-threaded on the outer end ofsaid 'st'ud, said nut having a separable part, a pin carried by said separable part of said nut, and means to secure together the two parts of saidnut.

11. A tension device comprising" a slotted stud having a screw-threaded outer portion, tension plates mounted on said stud, a casing having an apertured base to receive said Copies of-this patent may be obtained for five'cents each, by washin tongnfi c.

studand having a bar extending across said aperture to enter the slot in said stud, a spring coiled about said stud within said casing, a 'stop projecting inwardly from said casing, a nut comprising an apertured sleeve adapted to be inserted in the end of said casing and having a stop to cooperate with the stop carried by said casing, said nut having a boss adapted to enter the aperture in said sleeve when said nut has been screwed onto said stud, and means for rigidly connecting said sleeve with the body portion of said nut.

In testimony whereof, we 'aflix our'signatures in presence of two witnesses.

WILLIAM L. DAVIS. FRED L. VAN ALLEN. VVitIi'esse's:

- WILLIAM O. GRAY, J. CnARANcn Ln'srnn.

addressing the Commissioner of'Patents, 

